Influence of Ingesting a Carbohydrate-Electrolyte Solution before and during a 1-hr Running Performance Test

2009 ◽  
Vol 19 (6) ◽  
pp. 645-658 ◽  
Author(s):  
Ian Rollo ◽  
Clyde Williams
Keyword(s):  
Blood Glucose ◽  
Electrolyte Solution ◽  
Glucose Concentration ◽  
Performance Test ◽  
Respiratory Exchange Ratio ◽  
Blood Glucose Concentration ◽  
Double Blind ◽  
Running Performance ◽  
Double Blind Placebo ◽  
Trained Runners

The aim of this study was to investigate the influence of ingesting a carbohydrate-electrolyte solution (CHO-E) on performance during a 1-hr treadmill run. Eight male endurance-trained runners (age 31 ± 8 yr, M ± SD) completed three 1-hr performance runs separated by 1 wk. The study used a double-blind placebo (PLA) controlled design. On 2 occasions (P1, P2) runners consumed a placebo solution, 8 ml/kg body mass (BM), 30 min before and 2 ml/kg BM at 15-min intervals throughout the 1-hr run. On a separate occasion they consumed the same quantity of a 6.4% CHO-E solution (C). Total distances covered for P1, P2, and C trials were 13,685 ± 1,116 m, 13,715 ± 1,143 m, and 14,046 ± 1,104 m, respectively. Although there was no difference between the 2 PLA trials (p > .05), the distance covered during the C trial was significantly greater than in either PLA trial (p < .05). CHO ingestion resulted in a higher blood glucose concentration only at the onset of exercise (p < .05) compared with the PLA trials. Blood lactate, respiratory-exchange ratio, and CHO oxidation were similar in all 3 trials. In conclusion, ingestion of a 6.4% CHO-E solution before and during exercise was associated with improved running performance in runners compared with the ingestion of a color- and taste-matched placebo.

Comparison between Carbohydrate Feedings before and during Exercise on Running Performance during a 30-km Treadmill Time Trial

1994 ◽  
Vol 4 (4) ◽  
pp. 374-386 ◽  
Author(s):  
Costas Chryssanthopoulos ◽  
Clyde Williams ◽  
Wendy Wilson ◽  
Lucy Asher ◽  
Lynda Hearne
Keyword(s):  
Blood Glucose ◽  
Electrolyte Solution ◽  
Glucose Concentration ◽  
Blood Glucose Concentration ◽  
Time Trial ◽  
Treadmill Running ◽  
Endurance Running ◽  
Running Performance ◽  
Performance Times ◽  
Carbohydrate Meal

The purpose of this study was to compare the effects of a carbohydrate-electrolyte solution, ingested during exercise, with the effects of a preexercise carbohydrate meal on endurance running performance. Ten endurance-trained males completed two 30-km treadmill runs. In one trial subjects consumed a placebo solution 4 hr before exercise and a carbohydrate-electrolyte solution immediately before exercise and every 5 km (C). In the other trial, subjects consumed a 4-hr preexercise high-carbohydrate meal and water immediately before exercise and every 5 km (M). Performance times were identical for M and C, and there was no difference in the self-selected speeds. Oxygen uptake, heart rates, perceived rate of exertion, and respiratory exchange ratios were also similar. However, blood glucose concentration was higher in C during the first 20 km of the 30-km run. In M, blood glucose concentration was maintained above 4.5 mmol ·throughout exercise. Thus, the two conditions produced the same 30-km treadmill running performance time.

Metabolic effects of dobutamine in normal man

1992 ◽  
Vol 82 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Ceri J. Green ◽  
R. S. Frazer ◽  
S. Underhill ◽  
Paula Maycock ◽  
Judith A. Fairhurst ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Glucose ◽  
Glucose Concentration ◽  
Respiratory Exchange Ratio ◽  
Blood Glucose Concentration ◽  
Plasma Potassium ◽  
Metabolic Effects ◽  
Dobutamine Infusion ◽  
Plasma Insulin Concentration ◽  
Placebo Infusion

1. Dobutamine in 5% (w/v) d-glucose was infused at sequential doses of 2, 5 and 10 μg min−1 kg−1, 45 min at each dose, into eight healthy male subjects, and the effects were compared with those produced by infusion of the corresponding volumes of 5% (w/v) d-glucose alone. 2. The energy expenditure increased and was 33% higher than control (P<0.001) at 10 μg of dobutamine min−1 kg−1. The respiratory exchange ratio decreased from 0.85 (sem 0.02) before infusion to 0.80 (sem 0.01) at 10 μg of dobutamine min−1 kg−1, but did not alter during the placebo infusion (P> 0.001). 3. Plasma noradrenaline concentrations were lower during the dobutamine infusion compared with during the infusion of d-glucose alone (P < 0.025). Plasma dopamine concentrations remained below 0.1 nmol/l throughout both infusions. 4. Compared with during the placebo infusion, the blood glucose concentration decreased (P < 0.001), the plasma glycerol and free fatty acid concentrations increased by 150 and 225%, respectively (both P < 0.001), and the plasma potassium concentration decreased from 3.8 (sem 0.07) to 3.6 (sem 0.04) mmol/l (P<0.01) during dobutamine infusion. The plasma insulin concentration increased at 2 and 5 μg of dobutamine min−1 kg−1 (P<0.001) with no further rise at 10 μg of dobutamine min−1 kg−1. 5. Compared with during the placebo infusion, the systolic and diastolic blood pressures and the heart rate increased during dobutamine infusion (P<0.01). At 10 μg of dobutamine min−1 kg−1, the systolic blood pressure was around 160 mmHg (P < 0.001) and the heart rate was around 92 (sem 8) beats/min compared with 59 (sem 4) beats/min during the placebo infusion (P < 0.001). 6. Dobutamine has metabolic effects. It is markedly thermogenic and lipolytic. It depresses the respiratory exchange ratio and endogenous noradrenaline secretion, stimulates insulin secretion and depresses the blood glucose concentration.

Influence of Carbohydrate Ingestion on Blood Glucose and Performance in Runners

1992 ◽  
Vol 2 (4) ◽  
pp. 317-327 ◽  
Author(s):  
Randall L. Wilber ◽  
Robert J. Moffatt
Keyword(s):  
Blood Glucose ◽  
Glucose Concentration ◽  
Perceived Exertion ◽  
Treadmill Exercise ◽  
Blood Glucose Concentration ◽  
Endurance Performance ◽  
Time To Exhaustion ◽  
Experimental Conditions ◽  
Double Blind ◽  
Carbohydrate Ingestion

Ten trained male runners performed a treadmill exercise test at 80%under two experimental conditions, carbohydrate (CHO, 7% carbohydrate) and placebo (P), to determine the effect of carbohydrate ingestion on endurance performance (treadmill run time), blood glucose concentration, respiratory exchange ratio (RER), and subjective ratings of perceived exertion (RPE). Treatment order was randomized and counterbalanced and test solutions were administered double-blind. Ingestion took place 5 min preexercise (250 ml) and at 15-min intervals during exercise (125 ml). Performance was enhanced by 29.4% (p~ 0.05) during CHO (115 ±25 min) compared to P (92 ± 27 min). Blood glucose concentration was significantly greater during CHO (5.6 ± 0.9 mM) relative to P (5.0 ±0.7 mM). There was a significant increase in mean RER following CHO ingestion (.94±.01) compared to P (.90±.01). Average RPE was significantly less during CHO (14.5±2.3) relative to P (15.4±2.4). These data suggest that time to exhaustion of high-intensity treadmill exercise is delayed as a result of carbohydrate ingestion and that this effect is mediated by favorable alterations in blood glucose concentration and substrate utilization.

Metabolic Effects of Low-Dose Dopamine Infusion in Normal Volunteers

1990 ◽  
Vol 79 (6) ◽  
pp. 605-611 ◽  
Author(s):  
Cathy J. Regan ◽  
R. Duckworth ◽  
Judith A. Fairhurst ◽  
Paula F. Maycock ◽  
K. N. Frayn ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Fatty Acid ◽  
Blood Glucose ◽  
Free Fatty Acid ◽  
Energy Expenditure ◽  
Glucose Concentration ◽  
Respiratory Exchange Ratio ◽  
Blood Glucose Concentration ◽  
Metabolic Effects ◽  
Dopamine Infusion

1. Dopamine in 5% (w/v) d-glucose was infused into five healthy male volunteers at doses of 2, 5 and 10 μg min−1 kg−1 over three sequential periods of 45 min each. 2. Oxygen consumption, respiratory exchange ratio, blood glucose concentration and plasma levels of free fatty acids, glycerol, lactate, dopamine, adrenaline and noradrenaline were measured. The results were compared with values obtained during infusion over the same time period of the corresponding volumes of 5% (w/v) d-glucose alone. 3. Energy expenditure calculated from the oxygen consumption and the respiratory exchange ratio was higher than control values during infusion of dopamine (P < 0.001, analysis of variance) specifically at a rate of 10 μg min−1 kg−1 (P < 0.05) when it was 14% higher, but not at a rate 2 of or 5 μg min−1 kg−1. The plasma noradrenaline concentration was 74 and 230% and the blood glucose concentration was 21 and 36% higher than control values at 5 and 10 μg of dopamine min−1 kg−1, respectively (P < 0.01). At 10 μg of dopamine min−1 kg−1 the plasma free fatty acid concentration was 70% and the plasma glycerol concentration was 80% higher than during the control infusion (P < 0.01). The respiratory exchange ratio and the plasma lactate concentration were the same in the two groups and did not alter during the dopamine infusion. The plasma adrenaline concentration rose significantly (P < 0.01), but only transiently, during dopamine infusion at a rate of 2 μg min−1 kg−1. 4. Dopamine at low doses has metabolic effects. It increases the blood glucose concentration and the circulating noradrenaline level at an infusion rate of 5 μg min−1 kg−1. It increases energy expenditure and circulating free fatty acid and glycerol levels at an infusion rate of 10 μg min−1 kg−1, presumably due to stimulation of lipolysis.

scholarly journals The Comparative Effect on Satiety and Subsequent Energy Intake of Ingesting Sucrose or Isomaltulose Sweetened Trifle: A Randomized Crossover Trial

Nutrients ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1504 ◽  
Author(s):  
Fiona Kendall ◽  
Olivia Marchand ◽  
Jillian Haszard ◽  
Bernard Venn
Keyword(s):  
Blood Glucose ◽  
Energy Intake ◽  
Glucose Concentration ◽  
Crossover Trial ◽  
Blood Glucose Concentration ◽  
Area Under The Curve ◽  
Double Blind ◽  
Satiety Response ◽  
Diet Records ◽  
Significant Difference

The effect that blood glucose concentration has on feelings of satiety is unclear. Our aims were to assess satiety and subsequent energy intake following the ingestion of trifle sweetened with sucrose or isomaltulose whilst measuring plasma glucose concentration to confirm glycemic differences between trifles. Seventy-seven healthy adults participated in a double-blind crossover trial where trifle sweetened with sucrose or isomaltulose was consumed on separate days with a two-week washout. Blood was sampled at the baseline, 1 and 2 h postprandially, and satiety assessed using visual analogue scales (VAS). Weighed diet records were taken on test days. A statistically significant difference in blood glucose concentration between trifles was found at 60 min following consumption, with the isomaltulose trifle having a 0.69 mmol/L (95% confidence interval: −1.07, −0.31) lower concentration when compared with the sucrose trifle. Mean satiety response by area-under-the-curve (AUC) was not significantly different between trifles. Mean (SD) appetite scores for the sucrose and isomaltulose trifles were 4493 (2393) and 4527 (2590) mm·min, respectively, with a between trifle difference of −9 (95% CI: −589, 572) mm·min. Mean (SD) energy intake for the remainder of the day following trifle consumption was 3894 kJ (1950 kJ) and 3530 kJ (1926 kJ) after the sucrose and isomaltulose trifles, respectively, and was not significantly different (p = 0.133). The differing glycemic response to trifle was not related to satiety or to subsequent energy intake.

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